How we can iterate over all items in a storage map?

Question

I have a storage in pallet

pub type Users<T: Config> = StorageMap<_, Blake2_128Concat, T::AccountId, User>;

I need to iterate over all the storage map to check a field data inside the User structure.

Answer 1

StorageMap contains a function called iter() which returns a Iterator. So you can do something like this :

for (user_account_id, user_data) in Users::<T>::iter() {
    // Access the `User` structure using the user_account_id
    let user = user_data.ok_or("Error: User data not found")?;

    // Now you can check the field data inside the `User` structure
    if user.some_field == SomeValue {
        // Do something with the user's data
    }
}